Houston DWI Attorney - Cross Examination

Mastering Cross-Examination in DWI Cases: Leveraging Irving Younger’s 10 Commandments and NHTSA Standards

Houston DWI Attorney - Cross Examination

Houston DWI Attorney - Cross Examination

When defending a client in a Driving While Intoxicated (DWI) case, one of the most pivotal moments in trial comes during the cross-examination of the arresting police officer. The officer’s testimony—often rooted in their administration of the Standardized Field Sobriety Tests (SFSTs) as outlined by the National Highway Traffic Safety Administration (NHTSA)—can make or break the prosecution’s case. A skilled defense attorney can use this opportunity to expose inconsistencies, procedural errors, or lack of adherence to NHTSA guidelines, all while adhering to time-tested strategies like Irving Younger’s 10 Commandments of Cross-Examination.

Below, we explore how these principles intersect with the specifics of challenging an officer’s explanation of SFSTs in a DWI case.

Irving Younger’s 10 Commandments: A Framework for Success

Irving Younger, a renowned trial attorney and legal educator, distilled the art of cross-examination into 10 practical commandments. These rules provide a roadmap for defense attorneys to maintain control, avoid pitfalls, and effectively undermine the prosecution’s witness—here, the police officer. Let’s examine how they apply in the context of a DWI case, with a focus on the officer’s explanation of the SFSTs.

1. Be Brief

   
   

   Time is precious in cross-examination. Focus on key issues, such as whether the officer properly instructed your client on the SFSTs per NHTSA standards. Avoid lengthy tangents—zero in on discrepancies between the officer’s testimony and the NHTSA manual, such as failure to provide clear instructions for the Walk-and-Turn test.

   
   

2. Use Short Questions, Plain Words

   
   

   Complex questions can confuse jurors or give the officer wiggle room. Ask concise, straightforward questions like: “Did you tell the defendant to keep their hands at their sides during the Walk-and-Turn test, as required by NHTSA?” This forces a yes-or-no answer and highlights any deviation from protocol.

   
   

3. Always Ask Leading Questions

   
   

   Control the narrative by leading the officer to your desired conclusion. For example: “You didn’t demonstrate the One-Leg Stand for the full 30 seconds as NHTSA requires, correct?” This keeps the officer from elaborating unnecessarily and pins them to the facts.

   
   

4. Don’t Ask a Question to Which You Don’t Know the Answer

   
   

   Preparation is key. Review the officer’s body cam footage, arrest report, and the NHTSA manual beforehand. If the officer claims they explained the Horizontal Gaze Nystagmus (HGN) test correctly, but the video shows they skipped critical steps—like checking for equal pupil size—you can pounce on the inconsistency.

   
   

5. Listen to the Answers

   
   

   Officers may inadvertently reveal weaknesses. If they admit they didn’t verify whether your client had a medical condition affecting balance before the One-Leg Stand, you’ve just uncovered a violation of NHTSA’s pre-test screening requirements.

   
   

6. Don’t Quarrel with the Witness

   
   

   Stay calm and professional, even if the officer becomes defensive. If they insist they followed NHTSA guidelines but can’t recall specifics—like the exact wording of the Walk-and-Turn instructions—let their vagueness speak for itself to the jury.

   
   

7. Don’t Allow the Witness to Repeat Their Direct Testimony

   
   

   Officers often try to reinforce their story. Cut this off by redirecting them to specifics. Instead of letting them ramble about how “impaired” your client appeared, ask: “Did you ask if they wore contact lenses before the HGN test, as NHTSA mandates?”

   
   

8. Don’t Permit the Witness to Explain Their Answers

   
   

   Limit elaboration with tight questions. If the officer says they followed procedure, ask: “So you’re saying you held the stimulus 12 to 15 inches from their face during the HGN test?” If they hesitate, you’ve sown doubt without giving them room to recover.

   
   

9. Avoid Asking One Question Too Many

   
   

   Stop once you’ve made your point. If the officer admits they didn’t check for environmental factors—like uneven ground during the Walk-and-Turn—don’t press further and risk them backtracking or justifying their oversight.

   
   

10. Save the Ultimate Point for Summation

    
    

    Use cross-examination to gather ammunition, not to argue your case. If you’ve established the officer skipped NHTSA steps, let the jury connect the dots in closing arguments: sloppy procedure equals reasonable doubt.

    
    

NHTSA Standards and the Officer’s Explanation of SFSTs

The NHTSA has established three standardized field sobriety tests—Horizontal Gaze Nystagmus (HGN), Walk-and-Turn (WAT), and One-Leg Stand (OLS)—with strict guidelines for administration and explanation. Officers must adhere to these protocols, and any deviation can undermine the reliability of their observations. Here’s how a defense attorney can use cross-examination to challenge the officer’s adherence to these standards.

• Horizontal Gaze Nystagmus (HGN)

  
  

  The HGN test assesses involuntary eye jerking as a sign of intoxication. NHTSA requires officers to explain and demonstrate the test clearly: hold a stimulus (like a pen) 12-15 inches from the subject’s face, move it smoothly side-to-side, and check for distinct nystagmus at maximum deviation. Cross-examination can focus on:

  • “Did you confirm the defendant wasn’t wearing contacts, which NHTSA says can affect results?”

  • “How long did you hold the stimulus at maximum deviation—two seconds, or the required four?” Small errors here can invalidate the test’s scientific credibility.

    
    

• Walk-and-Turn (WAT)

  
  

  This test requires a straight line, nine heel-to-toe steps, and a pivot turn. NHTSA mandates clear instructions: keep arms at sides, don’t stop walking, and count steps aloud. Key questions include:

  
  

  • “Did you demonstrate all nine steps yourself, as NHTSA requires, or just a few?”

  • “Was the ground level and free of debris, per NHTSA guidelines?” If the officer rushed the explanation or chose a poor location, the test’s results are suspect.

    
    

• One-Leg Stand (OLS)

  
  

  The subject must stand on one leg for 30 seconds while counting aloud. NHTSA requires officers to ask about medical conditions and demonstrate the test fully. Probe with:

  • “Did you ask if the defendant had a leg injury before starting?”

  • “Did you time the test with a watch, or just estimate 30 seconds?” Failure to screen for physical limitations or follow timing protocols can render the test meaningless.

    
    

Why This Matters in Your DWI Defense

Police officers are not infallible, and the SFSTs are not foolproof. By combining Irving Younger’s commandments with a deep understanding of NHTSA standards, a defense attorney can expose flaws in the officer’s training, memory, or execution. Jurors don’t need to believe your client is innocent—they just need reasonable doubt. Every missed step, unclear instruction, or procedural shortcut uncovered in cross-examination builds that doubt.